sinew

A tendon.

Vigorous strength; muscular power.

The source or mainstay of vitality and strength.

To strengthen with or as if with sinews.

To furnish with sinews; strengthen as by sinews; make robust; harden; steel.

To serve as sinews of; be the support or mainstay of.

To knit or bind strongly; join firmly.

A cord or tendon of the body. See tendon.

A nerve. Compare aponeurosis.

Hence Figuratively, muscle; nerve; nervous energy; strength.